1. Field of the Invention
This invention relates to shades, fenestration treatments and the like and, more particularly, to flexible sheet structures which comprise collapsible, multi-celled curtains or planar coverings. Such multi-celled structures are generally used as moveable window shading and combine the art of planar coverings with that of honeycomb and similar structurings.
2. Discussion of the Prior Art
The prior art discloses various means for and methods of making multi-celled, collapsibly-flexible sheet structures. One of the earliest attempts to create such a structure was disclosed in patent U.S. Pat. No. 4,019,554, issued to Rasmussen in 1977. Rasmussen's invention comprises a plurality of superimposed, one-directionally arranged tubular members with a common slat-like partition, resembling the slat of the common Venetian blind, between each pair of adjacent tubular members. Each of the tubular members, which could be formed from a semi-rigid flexible fabric or material, has a folding crease along its two opposite sides; such a crease allowing the collapse of each individual tube and thereby permitting the entire structure to collapse in the manner of a Venetian blind. Rasmussen titled his invention THERMAL INSULATING CURTAIN, ESPECIALLY FOR USE IN GREENHOUSES. Thus, the inventor clearly taught the use of a flexible, multi-celled and collapsible sheet structure for the purposes of maintaining an insulative layer between two differing climatic environments. Aesthetically, the invention can be said to have been pleasing to the eye but, from a truly functional poiht of view, it lacked a mechanical holism that would have allowed its usage in not only greenhouse structures of the day but the greenhouses, sunrooms, and atriums of the next four or five decades. Rasmussen failed to provide the means whereby a multi-celled, collapsible and flexible sheet structure could be made to extend over non-vertical surfaces, especially as disclosed in the more sinuous designs to today's glazing architecture.
Before the aforementioned mechanical flexibility could be acquired in an invention such as the instant, a certain evolution had to take place. The tube-like cells of the Rasmussen invention would have to become more flexible, more homogeneous (i.e., the rigid slat would have to the removed), and becomes more easily produced, at less cost and by a less labor-intensive method of manufacture. Concomitant in this evolution would have to be the development of greater aesthetic character, for future shades would not only have to provide increased flexibility and versatility, as well as environmental utility but, since the new operational environment would be office and home use, they would have to be quite attractive. Thus began the development of what is commonly referred to as honeycomb shade structures.
In 1965, a patent was issued to A. Masuda, U.S. Pat. No. 3,164,507 for a Method of Making Cylinders for Raising and Transplanting Seedlings of Farm Crops. Masuda taught method for making honeycomb planters, that is, an array of tubular, hexagonal shells that comprised a plurality of individual tubules glued and stacked in a stylistic fashion which, when expanded by drawing apart the upper and lower margins, formed a multi-cellular array which was almost identical to the natural honeycomb structure, yet retained its collapsible character. Masuda began with an elongate strip of suitable fabric and folded the lengthwise lateral edges towards the center longitudinal axis of the fabric strip. The folds were made at slightly more than one third of the strip width, thereby mandating a slight overlap of the lateral margins as they were folded towards the longitudinal center. At the point of overlap, an adhesive was laid down on the outside margin of the first folded panel and the second folded panel was overlaid the adhesive margin. Thus, when opened, one observed a simple paper tube. Thereafter, a desired number of tubes were, in their folded configuration, laid parallel on a horizontal surface with a spacing between the margins of approximately one third the width of each folded tube. An adhesive strip was placed along the top side of the lateral margins of the tubes with the exception that no strip was placed on what were (preselected) outer margins of the structure. A second layer of folded tubes was then placed parallel to the bottom layer so that the lateral margins of each of the upper tubes overlapped and were superimposed above the adjacent glue strips of the lower level tubes. This created a series of spaced, parallel tubes at one level with the same array on the next upper level, but offset by about one-third width from the layer or level immediately below it. The next level up was then placed over the original level in parallel alignment with the second, thereby creating an alternating stacking of folded tubes, each level cojoined to the one above and below it at the lateral margins of each tube, overlapping approximately one third at each lateral margin. When the array was opened, the result was honeycomb structure comprised of myriad, adjoined hexagonal cells, the hexagonal shape being acquired by the deliberate overlapping and cojoining of two thirds of each tube. Thus, in the completed array, only two sides or one third of the total sides of each hexagonal shell were not rigidifield by the stiffended adhesion to another cell. Although this method making cylinders for transplanting seedlings served the inventor's purposes well, such an array would be far too inflexible to serve as a shade. Another disadvantage to the Masuda method of preparation would be the loss of light transmissivity and the unlikelihood of using more than a one-cell construction of the Rasmussen character, both because of the excessive amounts of adhesive used. That the product of Masuda lacks aesthetic character derives perhaps because the inventor wished only to transplant seedlings of farm crops.
The 1980's ushered in an era of innovation relative to honeycomb insulating materials. Relative to shade structures, the simple pleated shade, because of its appearance and similarity with the externally facing portions of a honeycomb structure may have inspired the concept of employing the honeycomb or multicellular array as an adjunct to the pleated shade. Quite apparently, the Rasmussen invention could be characterized as an ordinary Venetian blind over which one has laid, both front and back, a pleated shade and glued the troughs of the pleats to the front and rear edges of the slats. Dwelling for the moment of the simple pleated shade, there is realized in its embodiment a very inexpensive device, since it is readily made from a single continuous sheet of material. Unfortunately, the simple pleated shade invariably requires an unattractive visible mechanism, usually in the form of cords through the pleats, in order to actuate its movement. The stored mode for this device is very compact because the pleated material folds up to a closely-stacked dense pile. But, the insulating value of this design is very low, as the sheet in which the pleats are made must be necessarily thin and flexible; thus, a single layer of such material does not provide much conductive or convective barrier against an undesirable climatic environment. Further, when cords are used to guide and move the pleats, the holes through which the cords pass become direct leakage paths across the insulation. Relative to their use as coverings to span a non-vertical opening, such flexible pleats rarely have the instrinsic stiffness required for such usage.
In Sep. 1982, a patent issued to L.P. Brown, U.S. Pat. No. 4.347,887, disclosing a method of bonding a continuous web to itself at predetermined locations, to acquire upon expansion, a cellular structure consisting of a double row of rectangular cells, one row staggered from the other. The bonding septa of the row configurations are approximately one fourth to one half of a fold width wide and are of uniform width, to assure that the outward facing panels of Brown's resulting shade are parallel. The parallel outer surfaces, along with the coplanar inner surface of the cell array, comprise a triple glazing type of insulative array. The bonding or glue lines are clearly visible between the cell structures and the resultant product, having wide glue lines, is inflexible normal to the plane, so that its use in curvilinear operations is practically nil.
Considering now a later structure, and one more closely related to the instant invention, an expandable honeycomb material is constructed from a plurality of cellular tubes bonded together along their edges to form collapsible panels. Such an invention is disclosed in U.S. Pat. No. 4,450,027 issued to W. Colson, which is only reminiscent of the Masuda invention. The Colson invention improves greatly on the insulating value of the simple pleated design by providing, in effect, two such pleated shades back-to-back as was suggested by Rasmussen. The entrapment of air in the resulting tubular cells (between the faces of the structure), provides an effective barrier to conductive and convective heat transfer. Hereinafter, when the reader encounters the drawings of the instant application, notice may be taken of the exposition of Colson's cellular array at FIG. 1. Therein the reader will observe that the internal space (between the faces of the cellular structure) is effectively divided by ligaments at the cell boundaries. These ligaments, constituting the tube-contacting surface comprised of material and adhesive, provide a place for passing therethrough the actuating cordage or guide blades associated with deployment of the invention. By piercing only the ligaments, such cordage or guide blades may be passed through the area (corresponding to the slat partitions of Rasmussen) hidden from view and avoiding the reduction and insulating quality of the structure such as would be suffered by piercing either of the pleated faces. Such actuating means, as well as other similar means, are well-known in the art and employed extensively in Venetian Blinds. The Colson honeycomb design has the advantages of high aesthetic appeal but has only moderate thermal effectiveness. Also, the Colson design has a limited bond area that limits its structural stiffness, a factor required for spanning non-vertical openings.
Lastly, in this discussion of prior art and the derivative chain of ideas, as well as disadvantages, which lead to the instant invention, is the invention disclosed in U.S. Pat. No. 4,307,768, issued to J. Anderson. This design, of an expandable honeycomb material, is one of the first truly honeycomb structures applied to window treatments and, although it precedes Colson, is a departure from such single-celled art. It is constructed from a number of individual flat sheets of flexible material attached to one another in a stack by applying alternate lines of bonding agent (such as glue) between the stacked sheets such that the bonding agent lies in the parallel lines on each sheet. The pattern of bonding lines is offset on every other sheet by one-half the line spacing distance. This provides an alternating pattern of lines through the stack of sheets, also reminiscent of Masuda who used a one-third alternate spacing and acquired hexagonal cells, which causes the sheets to flex when the top and bottom sheets of the stack are pulled apart from one another (as in Masuda). The flexing creates a number of internal tubular cells, a honeycomb, that will hereinafter be seen at FIG. 2. For comparison at this time, FIG. 2A is provided showing the stacking and gluing arrangement of Masuda. This prior art is taken directly from the Masuda disclosure. The Anderson structure provides some thermal advantage over that previously described by providing for multiple cells through the thickness of the shade structure. Unfortunately, there is provided no improvement in the manufacturability of the Anderson design because it still requires the bonding of a number of individual elements (the sheets) to form the final product. An overwhelming aesthetic disadvantage to the Anderson product is the presence of the sheet raw edges (and the bonding lines) on the faces of the structure that cannot go unnoticed. Advantageously, the multi-celled depth provides a high degree of intrinsic stiffness for spanning non-vertical openings, and the internal ligaments (such as observed in the Colson invention) provide hidden locations for actuation and guidance means. Anderson, in his teaching of lateral guide blades to afford means of guidance over which the honeycomb structure slides, passes the guide blade through the ligament array and claims an advantage of such ligaments in acquiring an improved edge sealing of the structure by virture of the twisting of the ligaments as the structure is expanded. Anderson teaches that, when a slot of a certain width is cut into the ligaments, so that the guide blade may reside therein and pass therethrough, slot edge contact made by the ligament and the blades effects a more complete sealing. Unfortunately, Anderson does not address the particular concern of the binding that must result when the contact between ligament and guide blade occurs. Such binding can prevent the full and uniform deployment of the structure and lead to premature wear and failure. Such a disadvantage, noticeable in vertical deployment of such a shade, can prove disastrous when one takes the shade to non-vertical, dynamic operation. Should the deployed shade remain static in a non-vertical posture, deformation of ligament edges will surely result with a loss of not only aesthetic appeal, but a good deal of the environmental seal that Anderson forecasts in the use of his invention.
That there exists a demonstrable need to provide for insulation of thermal openings, such as windows in buildings, can no longer be refuted. However, the vast majority of the applications require that the insulation be removable from time to time to provide for the admission of solar radiation and to allow an unobstructed view. Provision for such removal must be convenient and highly compact of storage, or the solution will be rejected by operators who will choose to leave the insulation in either the closed condition (thus defeating the purpose of the fenestration opening as to view) or in the open condition (thus defeating the purpose of the desired insulation). Further, since most such fenestration openings are in residential dwellings or workplaces where aesthetic conditions must be observed, it is essential that any proposed solution to the insulation problem provide for an attractive appearance in both the open and closed condition or, no matter how effective thermally, such a solution will not be implemented in a large number of sites where its insulating function is desirable. Contemporary use of proposed insulation mandates its provision at as low a cost as possible with greatest flexibility for use in varied thermal environments. The structure must be self supporting, consistent with its mobility so that it may be applied to non-vertical thermal openings, such as skylights or greenhouse structures. The instant invention provides all of the desirable characteristics described above, and successfully avoids the disadvantages of the prior art, even to the extent that, when fully collapsed, it presents minimal surface area susceptible to soiling.